1. Field of the Invention
The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display that is capable of displaying an image in one surface (an upper surface) or in two surfaces (an upper and a lower surfaces). The surface of image display can be selected by a user, and can be selected for a time period set by a user. The organic light emitting display of the present invention has a controlling unit that changes between an opaque state and a transparent state, and the controlling unit controls transmission of light to display an image on one surface or on two opposite surfaces of the organic light emitting display.
2. Description of the Related Art
Demands on personal computers (PC), car navigation systems, personal digital assistants, information communication devices, and combined products of the above have recently increased with the advent of an information oriented society. The above-described products require characteristics of high visibility, a wide view angle, and a high response speed to display moving images. A flat panel display (FPD) is suitable for the above characteristics so that the FPD has been attracted as a next generation display.
In general, a thin film transistor (TFT) has widely been used as a switching device that operates each pixel in a display device such as an organic light emitting display (OLED) or a liquid crystal display (LCD), etc. Therefore, significant attention is paid to fabrication of the TFT, and a FPD using more effective TFTs and a method of driving the FPD have been proposed.
A thin film transistor includes a semiconductor layer, a gate electrode, a source electrode, and a drain electrode. In general, the semiconductor layer, the gate electrode, the source electrode, and the drain electrode are made of opaque materials. In particular, the semiconductor layer is made of amorphous silicon or polysilicon. Because these materials are not transparent, there is limitation on increasing a width of a channel of the TFT when these opaque materials are used to manufacture a TFT that is used as a switching device of a transparent organic light emitting display. Because the width of channel is narrow, a large amount of current cannot flow into the channel, and a high voltage must be applied to the TFT. Therefore, there has problems that the light emitting device of the transparent organic light emitting display deteriorates and power consumption increases. Also, it is not possible to display an image on both surfaces of the organic light emitting display, because an amount of light passing through the opaque TFT is blocked by the TFT.